Tumor necrosis factor (TNF) is an important cytokine involved in the signaling of a number of cellular responses including cytotoxicity, anti-viral activity, immun-regulatory activities and the transcriptional regulation of a number of genes. The TNF receptors (TNFR1 and TNFR2) are members of the larger TNF receptor superfamily which also includes the Fas antigen, CD27, CD30, CD40, and several other receptors (Smith et al., 1996, Cell 75, 959-962). Members of this family have been shown to participate in a variety of biological properties, including programmed cell death, antiviral activity and activation of the transcription factor NF-.kappa.B in a wide variety of cell types. In particular, death domain containing members of this family, such as TNFR1 and Fas, can induce programmed cell death through a shared .about.80 amino acid death domain (Tartaglia et al., 1993, Cell 74, 845-853; Itoh et al., 1993, J.Biol.Chem. 258, 10932-10937).
Additional intracellular death domain containing proteins are identified through yeast two-hybrid interaction cloning by virtue of their interactions with the death domains of death domain containing members of the TNF receptor superfamily. For example, TRADD has been shown to interact specifically with TNFR1 (Hsu, et al., 1995, Cell 81, 495-504) and FADD (Boldin et al., 1995, J.Biol.Chem. 270, 7795-7798; Chinnaiyan et al., 1995, Cell 81, 505-512) and RIP (Stanger et al., 1995, Cell 81, 513-523) interact specifically with Fas. In fact, death domains define interaction domains that provide both homotypic and heterotypic associations and can function as adapters to couple members of the TNFR superfamily with other signaling proteins (see, e.g. Hsu et al. (1996) Cell 84, 299-308).
Accordingly, the ability to exogenously modulate the activity of death domain containing proteins would yield therapeutic application for numerous clinical indications. In addition, components of such pathways would provide valuable target reagents for automated, cost-effective, high throughput drug screening assays and hence would have immediate application in domestic and international pharmaceutical and biotechnology drug development programs. The present invention provides novel modulators of death domains, their use, e.g. in drug screens, modulating cellular function, etc.